Transmission of transgenic mosquito-killing fungi during copulation

Tuesday, November 15, 2022

10:48 AM – 11:00 AM PT

Location: Vancouver Convention Centre, Meeting Room 220

Presenting Author(s)

Brian Lovett

Insect Pathologist
USDA-ARS
Ithaca, New York

Co-Author(s)

EB

Etienne Bilgo

Centre Muraz/Institut de Recherche en Sciences de la Santé
Bobo-Dioulasso, Houet, Burkina Faso
AD

Abdoulaye Diabaté

Centre Muraz/Institut de Recherche en Sciences de la Santé
Bobo-Dioulasso, Houet, Burkina Faso
Raymond St. Leger

Distinguished University Professor
University of Maryland
College Park, Maryland

Transgenic mosquito-killing fungi were found to be highly effective against malaria mosquitoes in laboratory bioassays and semi-field trials conducted in Burkina Faso in West Africa. These studies assaying a mosquito-killing fungus modified to express an insect-specific spider toxin (Hybrid toxin) under the control of a hemolymph-specific promoter identified a number of advantages to transgenic fungi compared to unmodified fungi. In particular, transgenically hypervirulent fungi killed more mosquitoes, killed mosquitoes faster, hampered development of offspring and showed higher effective persistence. Additionally, laboratory bioassays have demonstrated that fungal infection limits blood-feeding behavior and works synergistically with pyrethroid insecticides, even towards insecticide-resistant mosquitoes. The latter suggests that inclusion of fungal biopesticides into integrated vector management may bolster other control tools. Considering the ongoing development of mating-based strategies for mosquito-control, we investigated the ability of male mosquitoes to deliver infective fungal spores during copulation. In these laboratory and semi-field experiments, we assessed how long (1-48 hours post exposure) after treatment with fungal spores copulating males were infectious to untreated females. We designed these experiments to compare the efficacy of the hypervirulent fungus and the unmodified fungus under this application method. The low spore dose delivered to females during mating (~9 spores/female) underscored the increased efficacy of the transgenic fungus. While the transgenic fungus consistently increased mortality of mated, female mosquitoes in our bioassays, our results suggest that wild-type fungi could also contribute to the efficacy of control programs that involve release of male mosquitoes.